Ink-jet recording method techniques have rapidly advanced, and industrial inkjet printing presses which employ an ink-jet recording method in an industrial or commercial printing press for producing a number of printed materials are disclosed in various documents (see, for example, patent documents 1 and 2 and non-patent documents 1 and 2). These industrial inkjet printing presses are marketed under the trade names, for example, TruepressJet of Dainippon Screen Mfg. Co., Ltd., Prosper and VERSAMARK of Eastman Kodak Company and JetPress of FUJIFILM Corporation.
The industrial inkjet printing press exhibits a color printing speed which is ten to several tens times faster than an ink-jet printer for so-called SOHO or a large format printer, and which, though, varies depending on various printing conditions, and the printing speed of the industrial inkjet printing press is 15 in/min or more, and the printing speed of that of a higher speed type is more than 60 m/min.
The industrial inkjet printing press can deal with variable information and therefore can be applied to on-demand printing. Printing companies frequently employ a form of printing method in which printing for fixed information is made by a conventional printing press, such as a gravure printing press or an offset printing press, and printing for variable information is made by an industrial inkjet printing press. That is, both printing by a conventional printing press, such as an offset printing press, and printing by an industrial inkjet printing press are performed with respect to a single sheet of printing paper.
However, conventional coated printing paper, such as coated paper for offset printing, is unsatisfactory in the applicability to an industrial inkjet printing press, and cannot achieve satisfactory image quality as a commercial product due to a lack of the ink fixing property or a lack of the ink absorbing capacity. Conventional exclusive paper to an ink-jet printer is unsatisfactory in the applicability to a conventional printing press, such as an offset printing press, and causes printing failure, such as blanket piling, due to a lack of the coating layer strength, making it difficult to obtain satisfactory image quality as a commercial product. Further, the conventional exclusive paper to an inkjet printer is not intended to be used at a printing speed as high as that of an industrial inkjet printing press, and therefore is likely to lack the ink absorption speed or lack the appropriate diffusion of ink droplets when used in an industrial inkjet printing press. The individual factors are likely to cause the image to be stained or cause a white defect in the solid printed region, making it impossible to obtain a printed material having satisfactory image quality as a commercial product.
An ink-jet recording paper used according to a system in which an ink fixing agent is supplied to the recording paper before printing has been known, wherein the ink-jet recording paper has formed, on at least one surface of a support in a sheet form, a coating layer mainly made of an inorganic pigment and a binder, wherein the inorganic component/organic component ratio in any portion of the coating layer near the surface as determined by thermogravimetry is in the range of from 97/3 to 70/30, wherein when the total of the inorganic components in the whole of the coating layer is taken as 100 parts by mass, any of ground calcium carbonate, precipitated calcium carbonate, and kaolin or a mixture of two or more of these pigments is contained as the inorganic component in an amount of more than 95 parts by mass, wherein the average particle diameter of the whole of the pigments is 0.02 to 2.00 μm (see, for example, patent document 3).
Further, a pigment coated glossy paper for printing suitable for hybrid printing, which has excellent offset printability, and which has printability for a high-speed inkjet printer using an aqueous pigment based ink, has been known, wherein the pigment coated glossy paper for printing has an inner pigment coating layer and a surface pigment coating layer, wherein the surface pigment coating layer contains, as a pigment, precipitated calcium carbonate having an average short diameter of 0.8 μm or less, and, as a binder, a styrene-butadiene copolymer latex, or a styrene-butadiene copolymer latex and casein, or a styrene-butadiene copolymer latex and a styrene-acryl copolymer latex, wherein an aqueous solution of a water-soluble multivalent metal salt is applied to the surface pigment coating layer and dried (see, for example, patent documents 4 to 7).